kernel: Rearrange for 1.8

In 1.8 we want to streamline the kernel build process. Basically we
currently have multiple copies of the kernel source floating around
and the copying/compression/decompression is painful.

Lets assume we have a kernel source per machine since in most cases
this is true (and we have a sysroot per machine anyway). Basically,
instead of extracting a source into WORKDIR, then copying to a sysroot,
we now set S to point straight at STAGING_DIR_KERNEL.

Anything using kernel source can then just point at it and use:

do_configure[depends] += "virtual/kernel:do_patch"

to depend on the kernel source being present. Note this is different
behaviour to DEPENDS += "virtual/kernel" which equates to
do_configure[depends] += "virtual/kernel:do_populate_sysroot".

Once we do this, we no longer need the copy operation in
do_populate_sysroot, in fact there is nothing to do there (yay).

The remaining part of the challenge is to kill off the horrible
do_install. This patch splits it off to a different class, the idea here
is to have a separate recipe which depends on the virtual/kernel:do_patch
and just installs and packages the source needed to build modules on
target into a specific package.

Right now this code is proof of concept. It builds kernels and kernel
modules. perf blows up in do_package with issues on finding the kernel
version which can probably be fixed by adding back the right bit of do_install,
and adding a dependency of do_package[depends] += "virtual/kernel:do_install"
to perf. The whole thing needs a good write up, the corner cases testing
and probably a good dose of cleanup to the remaining code.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/meta/classes/kernelsrc.bbclass b/meta/classes/kernelsrc.bbclass
new file mode 100644
index 0000000000..11f04e9612
--- /dev/null
+++ b/meta/classes/kernelsrc.bbclass
@@ -0,0 +1,7 @@
+S = "${STAGING_KERNEL_DIR}"
+do_unpack[depends] += "virtual/kernel:do_patch"
+do_package[depends] += "virtual/kernel:do_populate_sysroot"
+KERNEL_VERSION = "${@get_kernelversion_file("${S}")}"
+
+inherit linux-kernel-base
+